1. Field of the Invention
The present invention relates to a resonator for ultrasonic bonding used to weld a bonding wire by ultrasonic waves for the production of a semiconductor device.
2. Description of the Prior Art
FIG. 4 shows a prior art ultrasonic bonding machine used for the production of a semiconductor device. When a bonding wire 101 such as a gold wire is caused to pass through a wire path 105 formed in a capillary 104 installed at the end of an ultrasonic horn 103 through a clamper 102, the end of the bonding wire 101 projecting downward from the end of the capillary 104 is moved down together with the ultrasonic horn 103 and the capillary 104 to be placed upon an electrode in an unshown semiconductor device or lead frame to be bonded and sandwiched between the electrode and the capillary 104, and the ultrasonic horn 103 and the capillary 104 are vibrated by ultrasonic waves to bond the end of the bonding wire 101 to the electrode.
However, since the capillary 104 is connected to the end of the ultrasonic horn 103 which is mounted to the ultrasonic bonding machine in such a manner that it is supported on one side in the prior art, the ultrasonic horn 103 is bent by pressure for bonding the bonding wire 101 to the electrode with a support point for the ultrasonic bonding machine as a fulcrum, whereby the bonding position between the bonding wire 101 and the electrode is slightly changed, thereby making it impossible to carry out suitable bonding.
It is therefore an object of the present invention to provide a resonator for ultrasonic bonding, which is able to carry out suitable bonding by supporting the ultrasonic horn on both side of the capillary to maintain the bonding position between the bonding wire and the electrode accurately.
Since the ultrasonic horn comprises support portions which are situated at minimum vibration amplitude points on both sides of the capillary for passing the bonding wire therethrough in the present invention, the ultrasonic horn is mounted to an unshown bonding machine by the support portions in such a manner it is supported on both sides. Therefore, when the end portion of the bonding wire is sandwiched between an object to be bonded and the capillary by predetermined pressure, the ultrasonic horn is bent at the bonding position between the bonding wire and the object to be bonded by the pressure for bonding the bonding wire to the object to be bonded, thereby making it possible to maintain the bonding position between the bonding wire and the object to be bonded accurately and to bond the bonding wire to the object to be bonded suitably. Since the ultrasonic horn is mounted to the bonding machine in such a manner that it is supported on both sides with the capillary as the center, pressure applied to the bonding wire from the capillary at the time of bonding is well balanced on right and left sides, thereby making it possible to use a thin wire, thick wire or wire coated with a polymer material as the bonding wire.